1. Field of the Invention
The present invention relates to content distribution technology, particularly technology for determining terminals to which content distribution is permitted.
2. Related Art
In recent years an increasing number of home networks are being set up to share contents between terminals connected by a network in a home environment.
One possible configuration of this home network involves providing a single router in a home environment, and connecting a content server for storing contents and various terminals, such as DVD recorders, video players and so forth, below the router. The router is the only device in the home environment connected to an external network. The content server stores contents acquired from the external network via the router, and individual terminals request the content server for contents, which the content server then distributes in response to the requests.
However, unrestricted distribution of contents is not permissible in view of copyright protection. Restrictions are thus needed to prevent contents whose usage is only permitted of home terminals from being distributed to terminals outside of the home environment.
Unexamined Japanese patent application publication 2001-285284 discloses technology for performing authentication and key exchange prior to contents being transmitted/received when transmitting and receiving devices have the same subnet address.
According to this technology, contents can only be transferred between terminals having the same subnet address. Nevertheless, there are calls for technology that suppresses the transfer of contents in situations in which, for example, there is a high risk of contents being stolen by a third party, even during communication between terminals having the same subnet address.